Composite separator and lithium-ion battery using the same

Abstract

There is provided a composite separator for a lithium-ion battery, including a polyolefin substrate and a coating layer containing a binder and inorganic particles formed on a surface of the polyolefin substrate, a hydrogen bond being formed between the binder and the inorganic particles. Also provided are a method for preparing the composite separator for a lithium-ion battery and a lithium-ion battery using the composite separator. The composite separator of the present application increases adhesion force between the substrate and the inorganic particles, thereby reducing detachment of the inorganic particles. By using the composite separator, the product quality of the battery is improved, and the risk of influencing the safety performance of the battery caused by the detachment of the inorganic particles in a production process is reduced.

What is claimed is: 
     
         1 . A composite separator for a lithium-ion battery, comprising a polyolefin substrate and a coating layer formed on a surface of the polyolefin substrate, the coating layer comprising a binder and inorganic particles, wherein a hydrogen bond is formed between the binder and the inorganic particles. 
     
     
         2 . The composite separator for a lithium-ion battery according to  claim 1 , wherein the binder comprises an aqueous binder containing —CO— or —CN functional group, and the inorganic particles contain —OH functional group. 
     
     
         3 . The composite separator for a lithium-ion battery according to  claim 2 , wherein the binder is formed by polymerizing one or more monomers selected from a group consisting of acrylate, alkenyl carboxylate, and alkenyl nitrile. 
     
     
         4 . The composite separator for a lithium-ion battery according to  claim 2 , wherein the binder further comprises carboxymethyl cellulose. 
     
     
         5 . The composite separator for a lithium-ion battery according to  claim 2 , wherein the inorganic particles are selected from a group consisting of boehmite particles, aluminum hydroxide particles, magnesium hydroxide particles, and combinations thereof. 
     
     
         6 . The composite separator for a lithium-ion battery according to  claim 2 , wherein D50 of the inorganic particles is smaller than 3 μm, and D100 of the inorganic particles is smaller than 15 μm. 
     
     
         7 . The composite separator for a lithium-ion battery according to  claim 1 , wherein a thickness of the composite separator is in a range of 6 μm-30 μm. 
     
     
         8 . The composite separator for a lithium-ion battery according to  claim 1 , wherein a thickness of the coating layer is in a range of 2-6 μm. 
     
     
         9 . The composite separator for a lithium-ion battery according to  claim 1 , wherein the coating layer is formed on a single surface or double surfaces of the polyolefin substrate. 
     
     
         10 . A lithium-ion battery, comprising the composite separator for a lithium-ion battery according to  claim 1 .